The preferred embodiments of the present invention relate to surgical navigation systems and techniques. In particular, the preferred embodiments of the present invention relate to an integrated surgical navigation system and fluoroscopic X-ray system.
Medical imaging techniques including X-ray, CAT (Computerized Axial Tomography), MRI (Magnetic Resonance Imaging), and ultrasound are well established. These techniques provide an examining physician with high resolution images useful for subsequent detailed study and diagnosis. Recently, however, surgical navigation techniques have been proposed that use pre-operative images for improving inter-operative visualization of patient anatomy. To that end, one or more of the pre-operative images are displayed for the surgeon during an operation, with a surgical tool superimposed on the image in the correct location.
The navigational challenges associated with using pre-operative images during surgery include establishing a known coordinate system with respect to the patient, registering pre-operative images in the coordinate system, and tracking surgical tool movement through the coordinate system. In the past, navigation systems, attempting to meet these challenges, were developed as separate and independent add-on systems to be connected to separate and independent imaging systems. The add-on navigation systems were designed as separate navigation units, and generally did not adhere to a standard or consistent communications protocol for communicating with the imaging system.
As a result, prior navigation systems 1) required significant additional floor-space (in an already overcrowded operating room environment), 2) did not support high speed digital data transfer to the imaging system, and 3) had no bi-directional command and control interface with the imaging system. The lack of bi-directional command and control with the imaging system make it difficult, if not impossible, to ensure that position information from the navigation system actually corresponded to the moment in time that the image was acquired. As a result, tracking errors arise, for example, in a C-arm type X-ray system performing fluoroscopy, when the C-arm moves. The tracking error may arise during the time interval between the point in time at which image acquisition is finished and the point in time at which the navigation information was obtained. Any tracking error is undesirable in surgical navigation.
Additionally, the external output ports of prior imaging systems were generally limited to NTSC or PAL video outputs. An NTSC or PAL video output represents an immediate reduction in resolution and dynamic range in comparison with the original digital image read out of an X-ray detector (e.g., a 1024xc3x971024 image). Thus, as a separate system, conventional navigation systems were limited to using a frame grabber connected to the imaging system output port to acquire lower resolution images for later surgical navigation. Furthermore, where DICOM was used to transfer images between the imaging system and navigation system, the DICOM overhead limited throughput to as little as one image every twelve seconds.
A need has long existed for a method and apparatus for fluoroscopic surgical navigation that addresses the problems noted above, and other problems previously experienced.
A preferred embodiment of the present invention provides a medical diagnostic imaging system. The medical diagnostic imaging system includes an X-ray source and X-ray detector, sensors tracking a position of at least one of a surgical instrument and the X-ray detector, and an integrated imaging and navigation workstation. The integrated imaging and navigation workstation includes at least one processor executing fluoroscopic imaging based on an output of the X-ray detector and navigation tracking of positions of a surgical instrument and positions of an X-ray detector with respect to a coordinate system. The integrated imaging and navigation workstation also includes an input receiving surgical instrument tracking signals from the sensors, an input receiving detector tracking signals from the sensors, and a display for displaying fluoroscopic images with a displayed instrument superimposed. In particular, one or more relations of the displayed instrument with respect to the fluoroscopic image (e.g., coordinate location and rotation) corresponds to the relation of the surgical instrument to the patient.
Another preferred embodiment of the present invention provides a diagnostic imaging system communication protocol. The communication protocol implements bi-directional communication between a medical imaging subsystem and a medical navigational subsystem. The communication protocol includes a set of navigation subsystem to imaging subsystem messages as well as a set of imaging subsystem to navigation subsystem messages. The imaging subsystem to navigation subsystem messages include a start imaging and end imaging message. The messages may include Ping response time messages, system configuration, file request, image request, and image reply messages, as examples.